Too many? The secretary of Defense says we don't need all our aircraft carriers, like USS George Washington, seen here among US and Japanese warships during military exercises this month.AFP/Getty Images

On the night of Dec. 29, 1940, 70 years ago, President Franklin D. Roosevelt went on the radio to awaken Americans to a looming darkness on the horizon, even as they sat snug and secure digesting their post-Christmas dinners.

He warned of a growing totalitarian threat in the world bent on creating a new global order, one with “no liberty, no religion, no hope.” He spoke of the fall of France to the Nazis, of China invaded and Britain besieged. The idea of freedom itself was at peril.

It was up to Americans, he said, to reverse the tide of decline. “We must be the great arsenal of democracy” and put our “resources and talents into action” to face the still-distant threat.

After slumbering through the isolationist ’30s, America finally awoke to the fact that it lived in a dangerous world in which no nation could live as an island — and that America’s economic strength had to be matched by its military strength; indeed, the two were inseparable.

Today, we need a similar

wakeup call.

The talk in Washington these days is about cutting back on defense to ease the budget and winding down the war in Afghanistan and our presence in Iraq. Our Defense secretary wonders openly why we need so many aircraft carriers. The most popular military analysts all argue that somehow our military can do more while spending less.

Once again, the forces of darkness are gathering — slowly but inexorably. It’s true no world war is looming. But no one in December 1940 guessed that Pearl Harbor was coming in less than a year, either.

Europe isn’t in flames as it was when FDR spoke, but it is in turmoil — and its future in doubt. The march of democracy around the world, for the first time in two decades, is in retreat. Rogue nations Iran and North Korea build their nuclear arsenals, as one round of diplomacy after another fails to halt them.

Meanwhile, our two great adversaries during the Cold War, Russia and Communist China, grow their navies and arsenals and make their strategic presence felt around the world, even as ours recedes.

The trend is alarming. Our real defense budget — excluding the overhead costs of Iraq and Afghanistan — has shrunk to its lowest level compared to GDP, to less than 3.6 percent, compared to the average in time of peace of 5.7 percent. Even Bill Clinton before 9/11 managed 4.5 percent.

That’s the bad news. The good news is that every time we reassert our strength, we also spur our economy. During World War II, our GDP virtually doubled. President Ronald Reagan’s Pentagon spending in the ’80s helped to fuel the most uninterrupted period of growth in American history. The George W. Bush years saw a similar growth of the defense budget while unemployment fell to less than 5 percent.

The truth is every dollar spent on defense goes into real hardware and real jobs, even union jobs. By one estimate, just a 5 percent boost in the Pentagon’s operations and maintenance budget could create as many as 300,000 jobs. A similar boost in research and development for things like robotics, missile defense, new remote-guidance technology and cyberwarfare would reverberate through the economy and could boost our GDP by billions a year.

A strong military is our economic stimulus. By becoming strong and vigilant once more, and by allowing our military to rebuild and integrate emerging technologies with our existing forces, we can be a pillar of strength for the world — and for ourselves.

Dec. 29, 1940, marked the date when America, having lost its way, regained its confidence and found the tools to support democracy abroad and build a military second to none. An economy battered by depression and mismanagement from Washington regained its energies and roared back to life — and a world with tyranny looming on all sides found a beacon of hope in America and drew the material and spiritual tools for its salvation.

We’re still the biggest economy in the world, just as we’re still the defender of the sea lanes and guardian of global stability. We still have the finest business minds and engineers,and we are still the home of innovation, from missile defense and stealth technologies to Google, Apple and Oracle.

These are forces only waiting to be unleashed in 2011. As Roosevelt said, “We have every good reason for hope — hope for peace, yes, and hope for the defense of our civilization” — and for the cause of liberty and freedom.

Arthur Herman, an American Enterprise Institute visiting scholar, is writing a book on the Arsenal of Democracy.